Research On The Preparation And Characteristic Of SnS Films As Solar Cell Absorbers By Two-stage Process

SnS has an energy gap of Eg≈1.3eV, which is very close to the optimum energy gap 1.5eV of solar cells, and it has a high absorption coefficient (α>104cm-1) and a high conversion efficiency of about 25%. In addition, elements Sn and S are abundant and non-toxic in nature. Therefore, it has its own advantage as an absorption layer of solar cells.In this paper, the SnS thin films have been prepared by two-stage process in different sulphurisation temperature and time. By analyzing the structures and optical and electrical properties of the SnS thin films, the optimum technique parameters of preparing SnS films have been obtained: the sulphurisation temperature being 200~ 220℃and the sulphurisation time being 60~90 minute. The results show that, in this condition the SnS films have good adhesion to the substrates, compact surface , energy gaps of about 1.45eV, and absorption coefficientαin the visible light range is greater than 6×104cm-1.In theory, the SnS thin films can also be prepared in the sulphurisation temperature being 280~290℃and the sulphurisation time being 20~40 minutes. But in this condition, the SnS thin films usually contained SnS2,Sn2S3 for excessive sulphur.In addition, heightening sulphurisation temperature and prolonging sulphurisation time will improve the adhesion of the films to the substrates, crystallization and uniformity of the thin films. When sulphurisation time is 30 minutes and sulphurisation temperature change from 180℃to 240℃, the atomic ratio S/Sn of the films increases from 0.72 to 1.08 and energy gap of the films increases from 1.44eV to 1.48eV with the increasing of the sulphurisation temperature. When sulphurisation time is 30 minutes and sulphurisation temperature is changed from 240℃to 310℃, the atomic ratio S/Sn of the films increases from 1.08 to 1.96 and energy gap of the films increases from 1.01eV to 1.72eV with the increasing of the sulphurisation temperature. When sulphurisation temperature is 220℃, the atomic ratio S/Sn of the films increases from 0.88 to 1.05 and energy gap of the films...